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ENV 20068.2 Tufte Design Principles Give the viewer the greatest number of ideas in the shortest space of time using the least ink in the smallest space Try to maximize the data-ink ratio Try to maximize the data density Show data variation, not design variation Tell the truth about the data

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ENV 20068.10 Exercise Calculate the data density for these two examples –Suppose area is 10 sq units of area Gender, height and weight recorded for 92 students –Density for gender breakdown = –Density for height-weight relationship =

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ENV 20068.11 Design Variation Fundamental purpose of a graph is to show changes in the data Design variation – where the same data is displayed differently for decoration - is to be avoided Leads to ambiguity and deception What is wrong with this?

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ENV 20068.14 Reflection.. But it is not an easy matter Consider this graphic –Rate it for data ink, data density and lie factor Discuss!

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ENV 20068.15 Show the Context Remember that integrity is important in data presentation Consider the graph opposite –Conclusions can be very different depending on what is shown Spanish alcohol consumption

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ENV 20068.16 Acknowledgements This work is largely inspired by ET – Edward Tufte Thanks to the following web sites: –http://www.infovis.net/printMag.php?num=109&lang=2http://www.infovis.net/printMag.php?num=109&lang=2 –http://home.ched.coventry.ac.uk/Volume/vol0/philosop.htm